JP5204476B2 - Plasma device - Google Patents

Description

  The present invention relates to an inductively coupled plasma apparatus used for plasma processing and microanalysis used in a manufacturing process of a macroelectronic device such as a semiconductor integrated circuit element and a liquid crystal display element, and more particularly to such an inductively coupled plasma apparatus. The present invention relates to a high-frequency introducing member that is a main part.

  In order to improve the performance of macroelectronic devices such as semiconductor integrated circuit devices and liquid crystal display devices and realize cost reduction, high-precision and high-speed microfabrication (dry etching, etc.) that can withstand large integration is a large area substrate There is a growing demand to realize on. For such microfabrication, processing using plasma is suitable, and there is an inductively coupled system as a technique for forming such plasma.

In the inductive coupling method, generally, a high frequency is applied to an antenna disposed outside the decompression vessel, and energy is supplied to electrons in the plasma by an electromagnetic field induced inside the decompression vessel via a high frequency introduction member provided in the decompression vessel. Supply and maintain plasma. This method is characterized in that a high-density plasma can be maintained in a relatively high vacuum (about 10 ⁻³ Torr). For this reason, the directivity of ions incident on the substrate to be processed is well aligned. For example, when used for dry etching, the perpendicularity between the substrate surface and the processed surface is high, and high-frequency processing can be realized. Further, since a large amount of ions can be drawn from the plasma into the substrate to be processed, it is suitable for high-speed processing.

  In addition, when inductively coupled plasma is applied to dry etching technology, it is necessary to apply a high-frequency bias for attracting ions to the substrate to be processed separately from the high-frequency for plasma formation. The high-frequency bias current flows from the substrate to be processed into the plasma through the cathode sheath and from the plasma through the anode sheath into the wall of the decompression vessel. At this time, if the area of the decompression vessel serving as the anode is sufficiently (3 to 5 times) larger than the area of the susceptor electrode serving as the cathode, the potential difference between the plasma and the decompression vessel is reduced, while the plasma and cathode The potential difference between and becomes relatively large. Accordingly, the ion energy on the substrate to be processed becomes relatively large, and high etching efficiency can be obtained. On the other hand, since the voltage on the anode sheath side is relatively small, adverse effects such as exhaustion of the decompression vessel due to ion sputtering and contamination by the product are suppressed.

  By the way, since the induction electromagnetic field cannot pass through the inside of the conductor, conventionally, a dielectric (insulator) such as fused quartz or ceramic has been used as a high-frequency introducing member of the inductively coupled plasma apparatus. This portion is not included in the area of the anode because no high frequency bias current flows. Therefore, the larger the area of the high-frequency introduction member, the more difficult it is to secure the area ratio of the anode (conductive portion of the inner wall of the decompression vessel grounded to the ground) to the cathode (electrode on which the substrate to be processed is placed). Become.

  In particular, when processing a substrate having a large area, a hemispherical high-frequency introduction member 116 is conventionally disposed at a position facing the substrate 34 as shown in FIG. Although the spiral coil antenna 28 is arranged outside the high-frequency introducing member 116, the high-frequency introducing member 116 is made of only a dielectric, so that the metal decompression vessel wall 14 having a slight area on the side is provided. Only becomes the anode. In this case, since the area of the anode is almost the same as the area of the cathode, the potential difference between the plasma and the cathode is too small to decrease the etching rate, or conversely, the potential difference between the plasma and the anode increases. There has been a problem that ion sputtering becomes intense and wear of the decompression vessel 12 and metal contamination to the substrate to be processed 34 increase.

On the other hand, if the height or radius of the decompression container 12 is increased in order to increase the area ratio, the volume of the decompression container 12 increases. In this case, there is a problem in that the cost of the apparatus and the installation area are increased, such as a pump having a large exhaust capacity is required and the transport mechanism for the substrate to be processed 34 becomes large.

  The present invention has been made in view of such circumstances, and its main object is to provide a high-frequency introduction member that also functions as a counter electrode against a high-frequency bias and can contribute to an improvement in the degree of freedom in designing a plasma device. It is an object of the present invention to provide an inductively coupled plasma apparatus that uses an introducing member and can cope with an increase in the diameter of a substrate to be processed with high performance.

In order to achieve the above object, a high-frequency introduction member provided as a part of the decompression container to introduce a high-frequency electromagnetic field emitted from an antenna disposed outside the decompression container into the decompression container was first examined. In the present invention, in an inductively coupled plasma apparatus for processing a substrate to be processed,
A reaction vessel whose inside is decompressed, comprising a cylindrical vessel wall and a window which is a high-frequency introduction member attached to the upper portion of the vessel wall;
A susceptor which is disposed inside the reaction vessel and supports the substrate to be processed on the upper surface below the window;
A coiled antenna disposed around the window;
A high-frequency power source connected to the antenna via an impedance matching unit;
A high-frequency bias power source connected to the susceptor;
The window has a conductive thin film;
The conductive thin film has a permeability capable of transmitting a high-frequency electromagnetic field emitted from the antenna through the conductive thin film into the reaction vessel,
The conductive thin film was formed over the entire window.

  The decompression vessel serves as a support body that maintains the internal and external airtightness and withstands the internal and external differential pressure. In addition, a conductive thin film such as a metal thin film can be used as an electrode through which a high frequency bias applied to a substrate to be processed passes.

  The conductive thin film can transmit most of the electromagnetic waves emitted from the antenna by setting it to an appropriate thickness or less. In this case, the standard of the thickness of the conductive thin film is given in relation to the frequency applied to the antenna. That is, if the thickness of the conductive thin film exceeds the skin depth at the high frequency, the thin film cuts off the high frequency as much as the thicker metal. It is desirable that the thickness of the conductive thin film is sufficiently smaller than the skin depth.

  Moreover, even if the conductive thin film has a thickness greater than the skin depth, it can transmit most of the electromagnetic waves emitted from the antenna by being composed of a plurality of parts that are divided from each other and arranged along the transmission surface. I can do it. With such a configuration, it acts as a dielectric for electromagnetic waves from the antenna, and exhibits a conductive property for high-frequency bias. Therefore, even if this high-frequency introducing member is used for most of the decompression vessel, the area of the anode does not decrease.

  The plasma apparatus according to the present invention also includes a dry etching apparatus, a CVD apparatus, and the like.

  As described above, according to the present invention, a high-frequency introduction member that has both the advantages of being similar to a dielectric with respect to a high-frequency electromagnetic field and acting like a conductor with respect to a high-frequency bias voltage. Is used to provide a plasma device that suppresses adverse effects on elements such as electrostatic damage and contamination in a surface treatment process such as dry etching or a CVD device, and further reduces the consumption of members in a reaction vessel. be able to.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  FIG. 1 shows a dry etching apparatus 10 using inductively coupled plasma according to a first embodiment of the present invention. The dry etching apparatus 10 includes a reaction vessel (depressurized vessel) 12 whose inside is depressurized. The reaction vessel 12 is composed of a vessel wall 14 made of a metal material such as stainless steel and a hemispherical dome-shaped high-frequency introduction member, a so-called window 16 attached to the upper portion thereof.

  As shown in FIG. 2, the structure of the window 16 has a window main body 18 made of alumina. The entire inner surface of the window main body 18 has a thickness of 100 Å in order toward the inside of the reaction vessel 12. The titanium nitride thin film 20, the 200 Å thick titanium thin film 22, and the 100 Å thick titanium nitride thin film 24 are formed by an appropriate method such as sputtering. The inner surface of the titanium nitride thin film 24 is coated with an alumina film 26 having a thickness of 300 microns by plasma spraying. The titanium thin film 22 is electrically conductive and is grounded together with the container wall 14. Further, the titanium nitride thin films 20 and 24 above and below the titanium thin film 22 serve as barrier layers for preventing the titanium thin film 22 from reacting with oxygen atoms in the alumina ceramic and being altered. The window (high-frequency introducing member) 16 according to the present invention in which such thin films 20, 22, and 24 are laminated is hereinafter referred to as a laminated window 16.

  A high frequency antenna 28 for inducing a high frequency into the reaction vessel 12 and supplying energy for plasma maintenance is wound around the laminated window 16 in a spiral coil shape. A high frequency power supply 32 of 13.56 MHz, for example, is connected to both ends of the antenna 29 via an impedance matching device 30.

  Inside the reaction vessel 12, a susceptor 36 for placing a silicon wafer 34 as a substrate to be processed is disposed. An electrostatic chuck 38 for fixing the silicon wafer 34 is provided on the upper surface of the susceptor 36. The susceptor 38 also functions as an electrode and is grounded via a high frequency bias power supply 40. Accordingly, a high frequency bias voltage of 13.56 MHz, for example, is applied to the grounded container wall 14 and the titanium thin film 22 of the laminated window 16, and the susceptor 36 functions as a cathode and the container wall 14 and the titanium thin film 22 function as an anode. It is like that.

  Further, the reaction vessel 12 is provided with a gas supply port for introducing an etching gas supplied from a gas supply source (not shown) into the interior, and further, a vacuum pump (for exhausting the inside) ( An exhaust port 44 connected to (not shown) is provided.

  Next, the effect of the dry etching apparatus 10 will be described in comparison with the dry etching apparatus 100 having the conventional configuration shown in FIG. The conventional apparatus is assumed to have the same configuration as the apparatus shown in FIG. 1 except that the window 116 is made of only alumina and does not have a laminated structure. Moreover, in the dry etching apparatus 10 shown in FIG. 1, the area ratio of the upper surface (part which functions as an electrode) of the susceptor 36 with respect to the container wall 14 and the titanium thin film 22 was 2.0 and 4.5, respectively.

Table 1 shows the self-bias voltage Vdc (V) generated on the silicon wafer 34 and the bias power density (W / cm) when plasma is formed by the high-frequency antenna 28 to dry-etch the silicon oxide film on the silicon wafer 34. ² ). In this case, a gas mixture of CHF ₃ and Ar (CHF ₃ : Ar = 1: 5), which is a typical etching gas for a silicon oxide film, is supplied into the reaction vessel 12 at a flow rate of 200 sccm (cc ³ · atm / min). While introducing from the supply port 42, the internal pressure was maintained at 10 mTorr, high frequency power of 3 kW was applied to the antenna 28, and plasma was formed in the reaction vessel 12.

  Here, the self-bias voltage is a temporal average value of the bias voltage generated on the silicon wafer 34 that is capacitively connected to the susceptor (electrode) 36 through the insulator of the electrostatic chuck 38. . If ion scattering is almost negligible at a relatively low pressure, as in this example, the self-bias voltage corresponds approximately to the average energy of ions accelerated from the plasma toward the silicon wafer 34.

In etching a silicon oxide film, it is necessary to bombard ions with relatively large kinetic energy in order to induce an etching reaction. In the above example, it is necessary to obtain a self-bias voltage of 600V. Therefore, it can be seen from Table 1 that a bias power density of about 3 W / cm ² is required in the conventional dry etching apparatus 100 using the window 116 made of only a dielectric. Electrode for machining, namely the top surface of the susceptor 36 needs to be larger design than the area of the wafer 34, when processing silicon wafers 34 of 200mm diameter, the area of the susceptor top surface becomes 300cm ² ~400cm ^2. Accordingly, it can be seen from Table 1 that when the area of the upper surface of the susceptor is 400 cm ² , it is necessary to apply a bias power of 1.2 kW as a whole between the susceptor 36 serving as the cathode and the container wall 14 serving as the anode.

  When such a large bias power is applied, the temperature of the silicon wafer 34 is abnormally increased, or the etching rate of the photoresist film serving as an etching mask is increased to reduce the selectivity, which adversely affects the etching characteristics. Occurs. Furthermore, since the bias power of 30% to 40% of the energy input to the antenna 28 heats the plasma, there is a risk of adverse effects such as deterioration in uniformity and increase in electron temperature.

On the other hand, according to the dry etching apparatus 10 having the laminated window 16 according to the present invention, a self-bias voltage of 600 V can be generated with a bias power density of 1.0 W / cm ² or less. Therefore, the power applied to the entire susceptor 36 is also suppressed to 400 W or less, and can be suppressed to 13% of the power input to the high-frequency antenna 28.

  Table 2 shows the results of comparing the etching characteristics of the dry etching apparatus 10 according to the present invention and the conventional apparatus 100. When a bias power as high as 1200 W is applied to the susceptor 36 in the conventional dry etching apparatus 100, the etching rate is relatively high at 1050 nm / min, but the selection ratio to the photoresist and silicon is only 6.2 and 18, respectively. Absent. On the other hand, when a bias power of about 400 W is applied to the susceptor 36 in the dry etching apparatus 10 shown in FIG. 1, the etching rate is slightly reduced, but the selectivity is improved by 2 to 3 times. It was confirmed.

  The high frequency applied from the outside by the antenna 28 is shielded by the plasma in the space of about 20 mm from the inner surface of the window 116. For this reason, the region where the high frequency is consumed and the plasma is formed is limited to the region of about 10 mm to 20 mm from the inner surface of the window 116. The average kinetic energy of electrons in this part is relatively large, and is about 4 to 8 eV in terms of electron temperature. However, a distance of about 100 mm exists between this portion and the silicon wafer 34. Since the mean free path of electrons heated by the electromagnetic field in the plasma formation region is several mm, it diffuses into the afterglow region in the vicinity of the silicon wafer 34 while repeating a random walk movement of several mm per time. During this time, electrons diffuse while losing energy due to impact with gas molecules, and plasma with a low electron temperature reaches the silicon wafer 34.

  High energy electrons in plasma with a high electron temperature have a large directional random component when incident on the silicon wafer 34, so when entering into a narrow groove or hole, the ions are relatively aligned with each other. Causes imbalance, and causes charging at the bottom or side wall of the groove or hole. This charging causes the aspect ratio dependency of the etching rate and charge-up damage. For these phenomena, it is an extremely effective means to suppress the electron temperature of plasma when the silicon wafer 34 is disposed in the afterglow region and acts on the silicon wafer 34. However, since the conventional dry etching apparatus 100 needs to apply a relatively large bias power, the temperature of electrons tends to rise again in the vicinity of the silicon wafer 34.

  On the other hand, when the dry etching apparatus 10 provided with the laminated window 16 of the present invention is used, reheating is unlikely to occur because the bias power required for etching is relatively small. Table 3 shows actual measurement values.

  From Table 3, it can be seen that the dry etching apparatus 10 of the present embodiment achieves a lower electron temperature even when no bias power is applied to the susceptor. Although a relatively high voltage of 2 to 10 kW is generated at both ends of the external high-frequency antenna 28, the electric field generated by the antenna 28 reaches the inside of the reaction vessel 12 in the conventional window 116 made of only a dielectric. For this reason, a local high electric field is generated in the plasma sheath near the end of the antenna 28. This electric field increases the electron temperature. On the other hand, when the laminated window 16 is used, the electric field does not enter the reaction vessel 12 due to the shielding effect of the titanium thin film 22. For this reason, the electron temperature of the dry etching apparatus 10 of this embodiment becomes smaller. Furthermore, the electron temperature at the time of bias application is suppressed to ½, which is 4.0 eV in the conventional apparatus 100 and 2.0 eV in the apparatus 10 of the present invention.

  Table 3 also shows the frequency of electrostatic breakdown for MOS devices. The element used in this evaluation is a poly-Si electrode type MOS capacitor formed with a resist pattern having an aspect ratio of 5, and has a structure sensitive to the influence of the incident angle distribution of electrons and ions. The withstand voltage of the MOS insulating film after the plasma treatment was measured, and those with 8 MV / cm or less were determined to be defective. In the case of using the laminated window 16 according to the present invention, no defect occurs regardless of the presence or absence of a bias, but in the case of the conventional window 116 made of only a dielectric, about 20% of the defect is caused by application of bias power. It was confirmed that it occurred.

  Table 3 shows the results of processing the contact holes and obtaining the conductivity failure rate. In this test, after depositing a silicon oxide film having a thickness of 2.1 mm on the silicon wafer 34, a resist pattern having a line width of 0.40 mm was baked, and after etching, a metal wiring layer was buried to confirm the presence or absence of conduction. One test pattern includes about 10,000 contact holes and has a chain structure connected in series with each other. Therefore, it is determined as good only when all the holes in the test pattern are open. When the laminated window 16 was used, the defect rate was as small as 3.1%. The defect is at a level that can be considered to be mainly due to particles adhering to the silicon wafer 34. On the other hand, when the window 116 made of only a dielectric was used, defective openings were observed in all test patterns.

  When the electron temperature is high, the incident angle distribution is expanded and the electrons cannot reach the bottom of the contact hole having a large aspect ratio. As a result, the positive charge of ions cannot be canceled, and as a result, an electric field that pushes ions back near the bottom of the hole is generated, thereby inhibiting etching. This defective opening is a result of the etching at the bottom of the hole being stopped for this reason.

  From the above results, when the electron temperature is suppressed as in the case where the silicon wafer 34 is arranged in a part away from the plasma formation region, that is, in the downflow region, the electron temperature is regenerated due to the bias application particularly by using the laminated window 16. It is clear that the effect of suppressing the increase can be obtained. In addition, it has become clear that the etching characteristics are also improved. Furthermore, when the effect was confirmed by changing the pressure, when the following relationship exists between the distance (L) between the plasma formation region and the silicon wafer and the mean free path (l) of electrons at the pressure: It was also confirmed that this effect appears remarkably.

  L> 10 × l Therefore, the present invention is more effective in the configuration in which the silicon wafer 34 is disposed in the plasma downflow region, and the distance between the silicon wafer 34 and the plasma formation region is an average free process. In the case of 10 times or more, the effect is particularly remarkable.

  On the other hand, a technique is known in which the high frequency applied to the antenna 28 is amplitude-modulated or is intermittent as an extreme example. The purpose of these techniques is to form a plasma having a low electron temperature as in the case where the wafer 34 is disposed in the downflow region. It is possible to efficiently reduce the electron temperature by intermittently or modulating the high frequency at intervals of 10 msec to 100 msec. In this case as well, the present technology having an effect of suppressing reheating of electrons due to the bias high frequency is effective.

  Moreover, consumption of the material of the laminated window 16 and the container wall 14 is also suppressed by using the laminated window 16 of the present invention. That is, the energy of ions colliding with the inner surface of the laminated window 16 and the container wall 14 is greatly reduced. This is due to the following two points.

  As described above, a high voltage of several kV or more is generated at both ends of the high-frequency antenna 28. When the conventional dielectric-only window 116 is used, a high electric field of several tens of kV / cm is generated in the sheath between the inner surface of the window 116 near the end of the antenna 28 and the plasma due to this influence. Ions are accelerated toward the window 116 of the part. Even a chemically stable material such as alumina cannot avoid physical sputtering with high-energy ions. On the other hand, when the laminated window 16 is used, the high electric field at the end of the antenna is shielded by the titanium thin film 22 and does not enter the plasma. Therefore, the potential difference generated between the inner surface of the laminated window 16 and the plasma is substantially equal to the plasma potential (Vp), and sputtering by ions is suppressed.

  The second reason is that, when the laminated window 16 is used, both the container wall 14 and the titanium thin film 22 of the laminated window 16 act as an earth electrode fixed to the earth with respect to the bias high frequency, so The area of the electrode is increased, and the plasma potential (Vp) can be suppressed both in a direct current and in an alternating current (and a fluctuation component). For this reason, the energy of ions becomes extremely small.

The dry etching apparatus 10 according to the present embodiment is also effective for suppressing metal contamination on the silicon wafer 34. The characteristics of Si-MOS devices are significantly hindered by alkali metal and heavy metal contaminants adhering to the surface. For this reason, it is necessary to suppress the amount of contamination adhering to the surface in the etching process to about 1 × 10 ¹⁰ atoms per 1 cm ² . On the other hand, the material of the window main body and the container wall contains a large amount of metal elements that are a source of such contamination. When these materials are depleted, contaminating metal elements drift into the plasma, and a significant portion of them deposits on the wafer 34. However, when the laminated window 16 of the present invention is used, contamination by heavy metals such as Fe and Cr and light metals such as Na is all suppressed to about 1/10.

  In setting the thickness of the titanium thin film 22 of the laminated window 16, the optimum film thickness is selected according to the transmittance of the induction electromagnetic field to be transmitted and the impedance to the bias high frequency applied by the plasma apparatus to which this window 16 is to be used. The That is, firstly, the transmittance of the high-frequency electromagnetic field from the external high-frequency antenna 28 is so large as to be practically acceptable, and secondly, the potential distribution in the surface of the titanium thin film 22 connected to a fixed potential such as the antenna potential. However, the thickness selection condition is that the resistance value is small enough not to cause a practical problem to the plasma. In the following consideration, the titanium nitride thin films 20 and 24 are extremely thin and do not affect the transmittance of the high-frequency electromagnetic field.

One of the guidelines for giving high-frequency electromagnetic field transmittance is the skin depth of the metal, which is given by the frequency of the induction electromagnetic field to be transmitted, the resistivity of the metal thin film, and the magnetic permeability. The skin depth (d) is expressed by the following formula.
d = (2 / ωμσ) ^1/2
Here, ω, μ, and σ are the high-frequency angular frequency, the permeability of the metal thin film, and the conductivity, respectively.

  In general, electromagnetic waves cannot penetrate into a sufficiently thick conductor. In particular, when the thickness of the metal thin film exceeds the skin depth, the electromagnetic wave is shielded almost as much as the thicker film and cannot be transmitted. Therefore, the skin depth is an index indicating the upper limit thickness of the titanium thin film 22 in the laminated window 16. In order to obtain a transmittance with a loss that can be ignored (1 to 10%), it is desirable that the thickness be 1/1000 to 1/100 or less of the skin depth.

  In the case of titanium, the skin depth has a value of about 30 microns for a high frequency of 13.56 MHz, for example. On the other hand, the potential distribution in the thin film plane depends on the current value of the high frequency bias, the shape of the laminated window 16, the connection method to the ground, and the like. As a rough guide, the effect is exhibited if the surface resistance value is 100 kW or less. In the case of titanium, this condition is satisfied if the thickness is 4 angstroms or more. Therefore, in the case of titanium, these conditions are satisfied if a thin film having a thickness of about 4 to 3000 angstroms is used. However, since the resistivity in such a thin film state may be larger than the bulk resistance value depending on the film forming means, it can be appropriately selected and used within a range of about 10 to 3000 angstroms.

  On the other hand, the innermost alumina film 26 protects the titanium thin film 22 from active species having high corrosion and etching properties such as halogen-containing gases such as fluorine and chlorine contained in the etching gas, or oxidizing gases such as oxygen and nitrogen dioxide. It is provided for this purpose. The alumina film 26 hardly reacts chemically with these active species and is suitable as a material for the protective film.

  On the other hand, since the alumina film 26 is a dielectric, it functions as a capacitive resistance sandwiched between the titanium thin film 22 and the plasma. Therefore, when the thickness of the alumina film 26 is unnecessarily large, the resistance to the high frequency bias is large, and there is a possibility that the effect of inserting the titanium thin film 22 is offset.

However, the effect is not lost if the capacity of the alumina film 26 is equal to or greater than the capacity of the plasma sheath formed between the plasma and the laminated window 16. In the case of low-temperature plasma having a density of about 1 × 10 ⁹ / cm ³ to 1 × 10 ¹¹ / cm ³ used in a normal etching process, the thickness of the plasma sheath is about 1 mm to 0.1 mm. Therefore, the thickness T of the alumina film 26 is preferably set so that the effective thickness obtained by dividing the thickness T by the dielectric constant ε is smaller than these values. Table 4 shows this relationship.

  The protective film is not limited to the alumina film 26. In the case of the same plasma conditions, the thickness of the internal protective film can be set large by using a material having a higher dielectric constant. In particular, when the thickness exceeds 1 mm, ceramic formed by sintering can be used as a protective film. Furthermore, when the thickness exceeds 10 mm, it is possible to maintain the pressure difference between the inside and outside of the reaction vessel only by this portion. In such a case, a high dielectric ceramic film such as titania may be used as a protective film, and a titanium thin film may be formed on the outer surface thereof, that is, on the window body side.

  FIG. 3 is a schematic diagram illustrating another embodiment of a dry etching apparatus constructed in accordance with the present invention. In this embodiment, the laminated window 216 is not hemispherical, but has a truncated conical shape and is substantially similar to the device 10 shown in FIG. 1 except that the antenna 28 is wound outside the conical surface. It is the same.

  In the laminated window 216, an alumina sintered body to which a small amount of titanium is added is used as a dielectric material for the window main body 218 and the protective film 226. The dielectric constant can be increased by adding titanium to the main component alumina.

  When manufacturing such a laminated window 216, first, a protective film 226 having a thickness of 3 mm is formed from an alumina sintered body having a dielectric constant of 50. Next, a titanium nitride thin film, a titanium thin film, and a multilayer film 250 of the titanium nitride thin film are sequentially formed on the conical outer peripheral surface of the protective film 226. Further, an alumina sintered body 218 having a thickness of 10 mm is joined to the outer surface thereof to form a laminated window 216 having the form shown in FIG.

  In the case of the illustrated embodiment, the top portion of the laminated window 216 is composed only of an alumina sintered body, and by providing a gap in the top portion of the outer window body 218, the tolerance generated during processing is absorbed by vertical displacement, and By forming a structure that allows air and gas remaining in the gap to escape during joining, formation of bubbles and peeling of the bonded portion are prevented.

  This manufacturing method has a feature that the inner surface in contact with plasma can be formed of a sintered body that can be easily controlled and processed, and is particularly suitable for forming a flat laminated window.

  FIG. 4 shows a third embodiment of a laminated window according to the invention. The laminated window 316 uses a titania sintered body as a dielectric material. In manufacturing the window 316, first, a titania sintered body 326 having a dielectric constant of 80 and a thickness of 15 mm is formed on the side exposed to the plasma. This functions as a protective film, but also functions as a window body that supports a metal thin film such as a titanium thin film. Next, a titanium nitride thin film 324, a titanium thin film 322, and a titanium nitride thin film 320 are formed on the outer surface of the titania sintered body 326. On these outer surfaces, a silicate glass coating layer 350 for protecting from moisture and oxygen in the air is formed.

  This structure is characterized in that the inner surface in contact with the plasma can be formed of a sintered body whose composition and purity can be easily controlled, and can be formed into various structures because it is relatively simple. In addition, this structure is particularly suitable for surface treatment that does not require high power to form a high-density plasma because the plasma density region that can be used is limited.

  FIG. 5 shows a fourth embodiment of the laminated window 416 of the present invention. The laminated window 416 has a cylindrical shape, and the antenna 28 is disposed so as to surround the cylindrical laminated window 416. The configuration itself of the laminated window 416 is substantially the same as that shown in FIG. 1, and as shown in FIG. 6, a window body 418 made of cylindrical alumina and a titanium nitride thin film 420 disposed on the inner surface thereof, The multilayer film 450 includes a titanium thin film 422 and a titanium nitride thin film 424, and a protective film 426 made of alumina disposed on the inner side thereof. Here, the multilayer film 450 does not extend continuously over the entire circumference, but is divided at a constant interval. For example, each multilayer film 450 is a rectangle having a long side of 50 mm and a short side of 10 mm, and is spaced 0.5 mm from each other so that the long side direction is substantially perpendicular to the current direction of the antenna 28. It should be arranged.

  When such a divided structure is used, it is possible to suppress a decrease in high-frequency transmittance even if a relatively thick titanium thin film 422 of about 30 μm is used. Further, the reduction of the electrode area is about 5%, and a sufficient effect can be obtained with respect to the bias current.

  Further, another multilayer film 470 composed of a titanium nitride thin film 460, a titanium thin film 462, and a titanium nitride thin film 464 is attached to the lower end surface of the laminated window 416, and its inner edge overlaps with the lower end part of the multilayer film 450. Are arranged in various forms. Further, a thin silicate glass film 480 is applied so as to cover the multilayer film 470. The multilayer film 470 forms a capacitor with the multilayer film 450 and enables capacitive connection with the reaction vessel wall.

  7 and 8 show still another embodiment. In the laminated window 516 according to this embodiment, a titanium nitride thin film 520 is deposited on one surface of a ceramic window body 518 made of alumina, titania or the like on a flat disk by a sputtering method, and then a 50 μm thick gold thin film 522 is formed by screen printing. A pattern is formed. The gold thin film 522 has a linear pattern extending radially from the center of the circular window body 518 toward the periphery and having a width of about 1 mm. Further, the gold thin film 522 is covered with a coating type silicate glass layer 526. The antenna 28 is arranged on the side opposite to the side on which these patterns are formed, and has a spiral structure.

  As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not restricted to the thing of the said embodiment.

  For example, in the above embodiment, the case where the present invention is mainly applied to a dry etching apparatus has been described. However, the present invention can be expected to have the same effect when applied to another process apparatus such as a plasma CVD apparatus. In particular, suppression of consumption of the reaction vessel and suppression of contaminants resulting from this are common issues for all microelectronic manufacturing technologies such as semiconductors and liquid crystal display elements. Inductively coupled plasma is also used for ultra-trace chemical analysis such as mass spectrometry and emission analysis. If the high-frequency conductive member of the present invention is used for these devices, the amount of interfering elements released from the reaction vessel is reduced, so that the minimum detection purity can be improved.

  Furthermore, in the said embodiment, although titanium and gold | metal | money are hung up as a material of the metal thin film used for a high frequency introduction member (lamination window), it is also possible to use another metal material and electroconductive material suitably. Moreover, it is also possible to use a dielectric material other than those described above.

It is a schematic sectional drawing which shows the dry etching apparatus of 1st Embodiment of this invention. It is an expanded sectional view which shows the A section of FIG. 1 schematically. It is a schematic sectional drawing which shows the dry etching apparatus of 2nd Embodiment of this invention. It is an expanded sectional view showing roughly other embodiments of a high frequency introduction member (lamination window) by the present invention. FIG. 6 is a perspective view schematically showing still another embodiment of the high-frequency introduction member (laminated window) according to the present invention. It is sectional drawing along the BB line of FIG. It is a top view which shows schematically another embodiment of the high frequency introduction member (laminate window) by this invention. It is sectional drawing along CC line of FIG. It is sectional drawing which shows the conventional dry etching apparatus roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Dry etching apparatus (plasma apparatus), 12 ... Reaction container (decompression container), 14 ... Container wall, 16 ... Laminated window (high frequency introduction member), 18 ... Window main body (high frequency introduction member main body), 20 ... Titanium nitride thin film , 22 ... titanium thin film (conductive thin film), 24 ... titanium thin film, 26 ... alumina film (protective film), 28 ... antenna, 32 ... high frequency power supply, 34 ... silicon wafer (substrate to be processed), 36 ... susceptor (electrode) , 40 ... high frequency bias power source.

Claims (11)

An inductively coupled plasma apparatus for processing a substrate to be processed,
A reaction vessel whose inside is decompressed, comprising a cylindrical vessel wall and a window which is a high-frequency introduction member attached to the upper portion of the vessel wall;
A susceptor which is disposed inside the reaction vessel and supports the substrate to be processed on the upper surface below the window;
A coiled high-frequency antenna disposed around the window;
A high frequency power source connected to the high frequency antenna via an impedance matching unit;
A high-frequency bias power source connected to the susceptor,
The window has a conductive thin film;
The conductive thin film has a permeability capable of transmitting a high-frequency electromagnetic field emitted from the high-frequency antenna through the conductive thin film into the reaction vessel,
The plasma apparatus, wherein the conductive thin film is formed over the entire window.   The plasma apparatus according to claim 1, wherein the conductive thin film of the window is grounded.   The plasma apparatus according to claim 1, wherein the container wall is conductive, and the conductive thin film of the window is electrically connected to the container wall.   The plasma device according to any one of claims 1 to 3, wherein the window further includes a thin film of a dielectric material laminated on the conductive thin film. The conductive thin film is a titanium thin film;
The thickness of the conductive thin film is within the range of 1/1000 to 1/100 of the skin depth of the metal constituting the conductive thin film with respect to the high frequency electromagnetic field emitted from the high frequency antenna, The plasma apparatus according to claim 4, wherein the window has a transmittance of 90% to 99% with respect to a high-frequency electromagnetic field emitted from the high-frequency antenna. The plasma apparatus according to any one of claims 1 to 5 , wherein the conductive thin film and the window are circular, and the conductive thin film is divided into a plurality of parts over the entire circumference. The conductive thin film is a titanium thin film;
The plasma apparatus according to any one of claims 1 to 6, wherein a thickness of the conductive thin film is 4 angstroms to 3000 angstroms.   The plasma apparatus according to any one of claims 1 to 7, wherein the window and the high-frequency antenna have the same shape.   The plasma apparatus according to claim 8, wherein the window and the high-frequency antenna have a hemispherical dome shape. The plasma apparatus according to claim 4, wherein the thin film of the dielectric material is laminated on an inner surface of the conductive thin film that is inside the chamber . The plasma apparatus according to claim 10 , wherein the window includes a titanium nitride thin film on an outer surface of the conductive thin film.

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